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-   -   Transmission Help (https://www.rx7club.com/v-8-powered-rx-7s-299/transmission-help-893973/)

fonzytank 03-22-10 01:16 PM

Transmission Help
 
Guys, I am rather desperately in need of help. I'm swapping a 305 sbc in my '86 FC 5-speed and trying to figure out a way to use my stock tranny. Please someone tell me there is a way to adapt it... Links, build threads, anything that could possibly help would be great!

2ndgencab 03-22-10 04:06 PM

Why a 305?? Anyways I dont think the fc tranny would be a good match for a v8. Even if your could mate them together. A 305 in a fc makes me LOL!!

fonzytank 03-22-10 04:15 PM

I'm sure you have a good reason to laugh at a 305, but since I'm new could you explain why? I'm looking for a budget build, and I need a manual tranny. The 350 makes too much torque for even a world class T5 so why not a 305?

RXSpeed16 03-22-10 05:55 PM

You'd need a custom bellhousing designed and machined to adapt the FC trans. Way more expensive than a T-5 or T-56. Remember that the NA trans is geared and built for a 140 lb-ft engine. How do you think it will perform/last behind a 305 sbc?

nillahcaz 03-22-10 06:46 PM

T-5 or T-56. I had a 305 in an FC for some time and it was a blast, I love how others talk shit with out ever driving / riding in a car with that combo.

fonzytank 03-23-10 07:50 AM

Guys thanks for everything and your right, I'm going to go T5, I just contacted Granny's and will be getting there mount kit.

RXSpeed16 03-23-10 09:59 AM

Good choice. If you're looking for more info, there's an engine swap section on this forum as well as v8rx7forum.

fidelity101 03-23-10 10:40 AM

boinger...

fonzytank 03-24-10 07:25 PM

fidelity, ya like the idea huh? I'll post up the build thread soon. Had the car 4 days. Half of the engine is out, and hopefully have the engine/tranny clear by the end of the weekend and also picking up the 305/t5 on sunday.

fonzytank 03-24-10 07:26 PM

Also can anyone who has done the sbc and or t5 swap chime in? Or PM me? Build thread suddenly becam reality lol fingers are too greasy to type

2ndgencab 03-24-10 07:46 PM

Im not talking shit. lol I was curious about the combo. Its unique. That stands for a lot! Gl! Keep us posted!

fonzytank 03-25-10 07:14 AM


Originally Posted by 2ndgencab (Post 9890765)
Im not talking shit. lol I was curious about the combo. Its unique. That stands for a lot! Gl! Keep us posted!

NO worries bro, didn't think you where! Just was wondering if you had thoughts lol. So half way through the tear down process and am starting a build thread today! And thanks for the luck man. I'm gonna need it on a 4wk schedule!!!

nillahcaz 03-25-10 10:21 PM


Originally Posted by 2ndgencab (Post 9890765)
Im not talking shit. lol I was curious about the combo. Its unique. That stands for a lot! Gl! Keep us posted!

Sorry, i get kinda pissy when some one questions the 305. I got a lot of shit for using it.

http://www.v8rx7forum.com/showthread...ild&highlight=

digitalsolo 03-26-10 09:57 AM

That's because it makes about the same power as a stock turbo rotary, with ~180 lbs more weight. :)

As long as you enjoy it though, that's what matters. Besides, at some point you can always swap something with power in it's place, the hard part is already done.

fonzytank 03-26-10 10:26 AM

The 305 makes the same HP but way more torque... Aka more smoke!!! lol and it definitely means the hard part is done for say a 350 or even a pretty much ready kit when you want to step up to an LSx (assuming the car survives that long)

digitalsolo 03-26-10 02:37 PM

There's a lot to change between an SBC and an LSx, even in an already V8 car. I know, I've done it. :)

Like I said, I'm sure it'll be fun. Definitely has torque. Just do better than the 305 powered FB that's local here; we're still looking for a car he can actually.. beat. It's sad really; one of the quickest cars at the lot is a rotary and the slowest is a V8 swapped RX7. :lol:

fonzytank 03-26-10 03:01 PM

digitalsolo, ouch thats a really sad story for us v8 swapped guys... I know as the motor sits now, a good turbo II is gonna eat me on the high way not off the light though!!! But with a cam/heads/and a few other things, I'll be running close to 300hp and 350tq's which will keep me happy for like 2mon lol And I won't be the chump at the local hangout. Then again, there really aren't any FC's around me (syracuse NY), and even less that drift....

nillahcaz 03-26-10 07:55 PM

the thing that kills the 305 for output can be a good thing, low compression ratio, add boost and enjoy. The swap from a SBC to a LSx is not too bad with the grannys kit if wiring is not something that bothers you. my build went 305 NA -> 305 turbo -> LH6 Twin turbo -> was offered $11,000 for the LH6, turbos, ecu, etc and went back to the 305 NA. The hard parts where the first 305 install and the fab for the twin turbos.

fonzytank 03-27-10 10:21 AM

I agree! And what people don't know, is that my car has no a/c or ps, plus lightened seats. So with a full tank of gas and me in the car, it currently weights in at aproximately 2990lbs with 49/51 bias actually to the rear.... Once turbo's are added (great minds think alike nillahcaz) it will be biased slightly forward

digitalsolo 03-29-10 10:13 AM

Shitty quench, cast pistons and poor headflow don't help the 305 either. What are you guys planning to do for fuel/spark control with turbos on that? TPI ain't gonna cut it.

And 11k for a turbo LH6? Ouch! Somebody got taken pretty hard there. I'd part with my forged 347" LS1 and turbo system for that price.

nillahcaz 03-30-10 04:42 AM

the best part is... they where cheap E-Bay turbo's I got from a buddy for $50 each... before you give me shit my S491's where out for rebuild and ceramic for hot side and powder for cold. He was more or less paying for the fab work as he loved how it looked and the GM MEFI4 ecu, cable and software. *awesome ECU btw*
It still makes me laugh, He put that setup in a 67 Camaro so it looks no where near as nice as it did in the 7 due to all the extra room in the bay.

fonzytank 03-30-10 11:43 AM

nillahcaz, is your 305 a tpi,tbi, or carbed? Mine is currently a carbed set up and I was intending to run a blow through style carb, and msd ignition with some ebay turbo's around 6psi on a stock bottom end 305 with about 30K on the motor. All channelled through a T5 till I have money for a t56. I have an N/A 86 FC and idea on the gears in the rear?

digitalsolo 03-30-10 02:54 PM


Originally Posted by fonzytank (Post 9902776)
nillahcaz, is your 305 a tpi,tbi, or carbed? Mine is currently a carbed set up and I was intending to run a blow through style carb, and msd ignition with some ebay turbo's around 6psi on a stock bottom end 305 with about 30K on the motor. All channelled through a T5 till I have money for a t56. I have an N/A 86 FC and idea on the gears in the rear?

That's a recipe for failure...

Stock, cast piston 305 + garbage turbos + T5 + N/A rear gears? Are you serious?

Blow through carb is going to require a good, competent tuner, and a good MSD should handle spark just fine, but the rest of that is either going to fail instantly, or fail catastrophically at an inopportune moment.

Save your money and do it right; it'll be cheaper than doing it twice, or selling the aborted project for a massive loss.

nillahcaz 03-30-10 09:36 PM

The car had two 305's they where quadrajet when NA. The turbo one got the MEFI, cheap summit forged pistons, etc. just a cheap build till I was done with the LSx *the LH6 in the end*
Im *as usual* with Digital on this one. I used forged pistons on an engine that was planned to be in the car for less than three oil changes and I would never add boost to any engine with cast pistons. The T5 can't hold the power of any thing more than a 283,305,327 and even a mild 327 can do a number on the world class. The NA gears are fine with a stock 305 or 350 but they are not built for power. Lastly if you pay more than $75 for an E-Bay turbo you are getting ripped off and still in the world of turbos the E-bay ones are good for place holders for fab work and to run on a Honda civic you're mom gave you. If you are looking to start cheap, drop an NA 305 in save and get an engine stand, save and get a good block, save and get forged internals, etc.

fonzytank 03-31-10 11:12 AM

digitalsolo, aren't you the guy who did/is doing the twin 67 turbo build on the 93 FD? I definitely respect your opinion. So I'm going to need to put a set of forged piston's in? And does the crank need to be replaced as well? How about the rods? I definitely intend to do the engine stand build that your talking about nillahcaz. But for the moment, I need to have the car running and making some decent torque for drifting. Whats the MEFI your talking about?


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